金剛般若經贊述 1.149

1.149

言三德者，謂戒、定、慧學。又說，一者、修行，謂具三學；二者、逢善友，謂值諸佛；三者、離空、有執，謂證二無我理。

As for the "three virtues," they refer to the trainings in morality, concentration, and wisdom. It is also said: first, cultivation, meaning being endowed with the three trainings; second, meeting good friends, meaning encountering various Buddhas; third, departing from grasping at emptiness and existence, meaning realizing the principle of the two kinds of selflessness.